Various patch bags have been commercialized for the packaging of bone-in fresh meat products, especially fresh red meat products and other bone-in meat products, such as whole bone-in pork loins, etc. The patch on the bag reduces the likelihood that the bag will be punctured by bones which protrude from the meat product.
It is desirable to provide a patch which covers as much of the bag as possible, while at the same time being both efficient to manufacture and efficient to use. In the manufacture of patch bags by a preferred process, the bag film is provided in the form of a continuous tubing, with the patches being adhered intermittently (or continuously) to one or both sides of the tubing. After the patches have been adhered to the tubing, the resulting tubing/patch laminate is converted into patch bags by heat sealing across the tubing and cutting across the tubing. Such seals are referred to as “factory seals” because they are made by the patch bag manufacturer, rather than the meat packer who makes a seal across the top of the patch bag. Both end-seal patch bags and side-seal patch bags have been manufactured in this manner.
More particularly, in the manufacturing process, efficiency has been gained by adhering a plurality of patches at repeating intervals to one or both sides of the continuous tubing, so that the seals later made across the tubing are in an area not covered by a patch. This allows for fast, efficient, and strong hermetic seals to be made, because heat need only be passed through the bag film, as opposed to both the patch film and the bag film. A disadvantage of the resulting product is that the seal area is not covered by a patch, and hence is more vulnerable to puncture. For some bone-in cuts of meat, having an uncovered seal area is a significant disadvantage, for example, if the particular bone-in meat cut has a sharp bone end in contact with the uncovered seal area of the patch bag.
In response to this disadvantage, more recently there has been developed a patch bag having a patch which covers the seal area. Such patch bags have been made by heat sealing through both the patch and the bag during conversion of the tubing/patch laminate to a patch bag. However, it has proven to be difficult to efficiently obtain high seal strength without burning through the patch and/or bag films, and it has also proven to be a much slower, less efficient conversion process than for patch bags in which the patch did not cover the seal area, as it has proven to be difficult to quickly heat the bag film to the required temperature for sealing when having to apply heat through the patch film. Special sealing means was developed to speed the sealing process and obtain the desired seal strength when applying heat through the relatively thick patch film.
It would be desirable to have patch coverage at the seal area without having to make the seal by passing heat through the patch film.